An asteroid colony

[chriscdc]

With all this talk of going to the moon, will we be missing out the advantages of the NEOs? The advantage of an asteroid base would be the low gravity. Any lunar base would need far more fuel to get to, and to get off, than an Asteroid.<br />How does the composition of an asteroid compare to the moon?<br /><br />I would personally favour colonising a C-type asteroid. Dig a tunnel into it and then hollow out a large sphere. Make the sphere air tight and you have a large living and working space. Moving large masses would require less energy than on the moon. <br />To remove mass from the sphere, you attach an ion thruster and point it out of the tunnel. Disconnect the ion drive from the mass and recycle the engine. If you start near the center of the asteroid the gravity will be tiny and you can reach escape velocity whilst you are still inside the tunnel and before you really start fighting the gravity.<br /><br />It will be easier to colonise one asteroid and then another then another using the same tech than to build a lunar outpost then to build an asteroid base. <br /><br />Even if there is little water on the asteroid, it would be easier to import it from earth than if you have to do the same for the moon.<br /><br />I would rather have 500m of asteroid above my head and on all sides, for radiation protection, than to have the moon on one side and only a couple of feet on the other.<br /><br />Does anyone know of a promising asteroid were this could be done?

 

[grooble]

We could turn the asteroid into a space station and some kind of depot.

 

[chriscdc]

The more I think about it the better it seems. You could colonise an asteroid that gets relatively close to mars at some point, then close to earth at others. You could save fuel by using some of the asteroids momentum. It could be re-used and would provide a better habitat than a cramped capsule.

 

[j05h]

asteroids have a ton of industrial potential. My current area of interest are near-Earth "dead" comets. There are several identified, but most of them orbit between Earth and Jupiter - the ideal candidate is an "Arjuna" class asteroid that has nearly identical orbit to Earth. For an ex-comet, there are several options for building habitats. My favorite is solar melting once you scrape off the crust. <br /><br />Here's the idea: tunnel several meters (or tens of meters) into the comet, then use a series of mirrors and lighttunnels to melt and process a large chamber. This can be done robotically, then the end of the tunnel can be capped for later habitation. Rocks, clay, metals and minerals are either saved in slag clumps or used for plating the tunnels. This process eventually (with many miner robots) creates a Swiss-cheese around the comet, these can be interconnected by further melting. Eventually most of the interior is liquified so that arctic/saltwater fish and crustaceans can be raised in it. Trees and crops can be grown near the surface, mangroves are used as a mat-structure to hold the crust together against the liquid interior. <br /><br />Eventually, this allows for a platform for growing space-adapted trees to live in: the trunk is partly hollowed, the branches are bubbled off for high-CO2 greenhouses and a ball of roots, cometary water and clay forms a large, brackish water habitat. the root-mass is protected with kapton and has traditional space-station components embedded in it for access. <br /><br />Another option with dead comets is taking some of the melt water and using it in double-bagged habs: the living space is inside several meters of water and plastic. <br /><br />ONce there, the possibilities with water, rock and microgravity are endless.<br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[mrmorris]

<font color="yellow">"Any lunar base <b>would need far more fuel to get to</b>, and to get off, than an Asteroid."</font><br /><br />This is incorrect unless the asteroid in question is orbiting the Earth (which would require <b>enormous</b> amounts of energy in and of itself). NEOs aren't just sitting out in space nearby waiting for someone to drop by -- they are in orbits about the sun that are different from Earth's. Their <b>position</b> is sometimes near that of Earth (although very seldom inside the orbit of the moon.. or even small multiples of the Earth-Moon distance), but even then, their <b>velocity</b> is markedly different. Matching velocity with them would take far more energy than that required to get to the lunar surface. Once *there*, getting materials off the surface would be easier -- but then getting it back to Earth, or the moon once again requires considerable dv.

 

[chriscdc]

I don't know the relative velocities of the asteroids but I'm sure there are some favourable ones out there. Wikipedia says there are some but doesn't mention any names. It does say that ones larger than 1km should number around 2000. Which gives alot of options.<br /><br />Ok, by 'to get to' I mean to carry the fuel to land and then to get off again.<br /><br />Unmanned vessels can be propelled by ion propulsion. To land on the moon you need chemical or nuclear thermal propulsion which obviously is very heavy. The gravity of an asteroid is so low that you could probably get to the surface by ion propulsion alone. <br /><br />On checking wikipedia.<br />The NEAR probe collided with 433 Eros with at only 4mph and it used a (hydrazine / nitrogen tetroxide) 450 newton (N) main thruster, and four 21 N and seven 3.5 N hydrazine thrusters for propulsion, for a total delta-V potential of 1450 m/s. Would it be possible to use an ion engine instead? What is the dv required to reach the moon, land and return.<br /><br />But the other advantage is in constructing the habitat. The energy required would be lower than for construction on the moon. You would hardly need to fight gravity at all. Therefore the strength of the machines could be lower and thus the mass would be greatly decreased. <br /><br />Getting humans there may be more difficult but construction would be easier. If we are planning on going further than the moon then the next stop will most likely be a NEO anyway. It would also be safer from a radiation and micrometerorite POV. The only problem would be that it would take longer to get back home.

 

[chriscdc]

A problem with using solar energy to vaporise the chamber through the tunnel is that the 'exhaust' would block a substantial portion of the beam. Also the particles would have a very straight velocity after coming out of the tunnel. The mirror would have to be directly above the tunnel to direct light through it. The mirror will get coated very quickly. <br /><br />I would rather use solar power, to power ion engines that could shift large blocks of material that would have been cut out.

 

[spacester]

There are two major factors when going elsewhere in the solar system, deltaV and timing.<br /><br />NEOs are (by definition) in orbits close to the Earth's orbit. If they are also in near-circular orbits, then their orbital velocity is close to the Earth's, so the dV requirement is in fact very modest.<br /><br />Add to that the fact that when you get there, IOW after you've matched the object's orbital velocity, it presents a much smaller gravity well to drop down into and return from.<br /><br />So it's easy to see how NEOs can require much less dV than the Planets. <br /><br />But what about in comparison with Luna? To get there, you don't even leave our gravity well to match heliocentric (sun-orbiting) velocities, but at the same time you have an expensive journey down and back to the surface. Yes, the Moon's gravity field is smaller, but it ain't exactly small. It still takes a good amount of propellant to operate on the moon.<br /><br />So it's not a straightforward comparison at all. As you change mission parameters (time of flight, plane changes, parking orbits, lunar location visited, etc) and select different NEO targets, it turns out that the dV requirements overlap.<br /><br />You can get to some NEOs for less dV than some lunar missions, and vice versa.<br /><br />The difficulty with NEOs is orbital timing. Anytime you're going out of our gravity well to match velocities with another sun-orbiting object, you have to choose a trajectory (a time of flight) and then you have to wait for Earth and the object to get to the correct relative position to make that trajectory work.<br /><br />By Keppler's laws, an NEO's orbital distance (semi-major axis) means that its orbital period is close to Earth's. So a year on a NEO is close to the same as a year on Earth. Now, picture these two rocks spinning around the sun and you can see that their relative position in their orbits changes slowly.<br /><br />It takes a long time for the two objects to come into the right position for la <div class="Discussion_UserSignature"> </div>

 

[chriscdc]

Ok so there may or may not be a suitable NEO out there.<br /><br />The reason why I want there to be a manned mission is that I believe it will be easier to colonise asteroid to asteroid than from planet to planet. Also a HLV can only lift up a small fraction of what will be needed to build a lunar colony, whereas 10's of tons to a NEO could achieve so much.<br /><br />The first trip would carry several things. There would be several hundred small explosives and microphones. You place the explosives over the surface as well as the microphones. You use the shock waves from the explosives to map out the inside of the asteroid.<br />You pick the best spot to place the habitat and you have a set of digging robots to carve out chunks of material. You could even use the ejected material to alter the course of the asteroid and make it more favourable to get to.<br /><br />You could collect carbon, oxygen and hydrogen to build explosives such as acetone peroxide. It will take time but you just have to slowly collect solar power. The explosives could then be used to make a larger habitat.<br /><br />Once you have a large enough space you put a large transhab in, minus most of the micrometerorite shielding. All of this could be done with only 1 HLV launch. Whilst a HLV trip to the moon might only carry a couple of cranes or a similar small number of other construction equipment. On the moon, to move blocks you still need steel cables whilst on an asteroid you might only need fishing wire.<br /><br />Perhaps you just need people who are willing to accept that they will not come back until they have manufactured the fuel to do so. Although you could probably generate the fuel needed to return, before anyone even launches from earth.<br />So whilst everyone else is concentrating on the moon, it could be possible to use 2 of the HLVs to get to an asteroid.

 

[spacester]

<font color="yellow">Ok so there may or may not be a suitable NEO out there.</font><br /><br />On the contrary, there are at least scores, probably hundreds, of wet NEOs out there waiting to be exploited as you describe. Sometimes I forget to mention that my perspective is always that of talking about what we can and should do in space in the very, very near term. Like, 'what should the next NEO mission be?' I favor a prospector mission before a space station building program, that's all. Plus I wanted to face up to the realities of orbital mechanics.<br /><br />I forgot the other trick to make NEOs more accessible schedule-wise. This trick is unconfirmed but my orbital mechanics understanding backs it up: Venus swing-by strategies can let you access a particular rock much more often, but at a delta V cost.<br /><br />If a prospector mission successfully identified several ore bodies (water and other mining) along with several objects suitable for your asteroid colonies, yes indeed an HLV flight could be sent to fully map out the interior, test digging technology and maybe the habitat as well. That would be quite a challenge, but it also would be a major step forward as a space-faring species.<br /> <div class="Discussion_UserSignature"> </div>

 

[chriscdc]

What programs are there out there to model such missions?<br /><br />As far as I know, C-type asteroids can contain large quantities of minerals that can contain up to 20% water. Apparently you only have to heat it to />200 degrees c, which should be no problemin a solar furnace. <br />There are also amino acids, plenty of oxides, magnetite ,silicates and sulphates.<br /><br />Currently going through the (rather long) lists of objects to find a possible candidate.<br /><br />The time scale i'm thinking of is the next 20years. Any short term missions would be interesting. <br /><br />edit /> Hey check out the Hayabusa mission. It is a sample return mission and will land on 25143 itokawa next month.

 

[chriscdc]

Found one.<br /><br />4660 Nereus. Was the original target for the hayabusa mission as well as a NEAP by spacedev (but this may or may not be defunct).<br /><br />Getting people there and back might be harder than the moon but I strongly doubt harder than mars. Getting machinery and resources there will be easy. Has an orbital period of 663 days. It does get a bit far out, approx 2 AU.<br />But it can be gotten to easier than the moon.

 

[spacester]

4660 Nereus (aka 1982 DB) is an interesting target. It is in an Apollo orbit, and at first glance it appears to require less dV than Mars without huge timing problems. IIRC we think it is loaded with good stuff.<br /><br />The Atens with very low eccentricity are the ones I'm going to try to analyze, here are the first 6 targets I've found<br /><br />1993 DA<br />2001 ED18<br />2001 FR85<br />2002 AA29<br />2003 YN107<br />2005 CN61<br /><br />Does the <i>orbiter</i> program have the capability to do the analysis? (My ancient PC is getting replaced soon, and I don't want to install orbiter until I get the new box.) <div class="Discussion_UserSignature"> </div>

 

[arobie]

Cool! Targets!<br /><br />Yes, the orbiter does have the capability to do the analysis of the Dv to any target you choose, but it does not (atleast to my knowledge) include asteroids and NEOs in the solar system. It would make the simulator too complex and severly decrease the running speed. On my computer, the simulator would not even run with all the extra bodies to keep account of.<br /><br />Hmm...before I continue, I want to say that I would of course not depend on Orbiter for 100% accurate data as for timing and dV and so on. I'm not sure how accurate the software is. Although I think you could depend on the accuracy to give you an idea of how much dV it would take to get from LEO (You choose the orbit) to asteroid so and so.<br /><br />Since there are no already made in-game asteroids, you have a couple options: You can either make the asteroid yourself and place it in its correct orbit for you to rendevous with, but making things is hard and time consuming. You can take an asteroid looking moon (Phobos, Deimos) already made and place it in any of those asteroids orbits, or you can just do the calculations to find out where so and so asteroid will be at on so and so date and plot the course and burns for your spacecraft to get there at the correct time. Either of the last two options are easy enough.

 

[chriscdc]

Well we really just need to know the dv, travel times and windows. I have never tried Orbiter before, so I will have to spend several days just getting to grips with it.<br />Phobos and Deimos are about the average size and shape of the targets, so all that really needs to change is the mass and rotation.

 

[chriscdc]

Good to see there are some. Many of them seem rather small. <br />2001 FR85 may be an old rocket, as it seems very small and the orbit is very close to earths.<br />2002 AA29 doesn't get closer than 5.6million km which could make getting there hard at the best of times. It is currently retreating and it will take 95 years to catch up behind us. Does that mean in 47.5 years it will be on the otherside of the sun (I might be wrong as I am still trying to understand the horse shoe orbit).<br />2003 YN107 is another of those wierd quasi moons. That will 'stop' being a moon in 2006.<br />2005 CN61 seems very small, but has an orbit very similar to earths and stays very close.

 

[chriscdc]

Just checking them on http://neo.jpl.nasa.gov/orbits/.<br /><br />99942 Apophis aka 2004 MN4 looks rather good and might give a good view of venus.<br /><br />I wonder how easy the asteroid jumping would be. It certainly looks attractive especially if the colony can become self sustaining. There are many possibilites of where to go after the first asteroid is set up to act as a refueling base.<br />

 

[spacester]

Cool, thanks for checking that out. All I did was grab the super-circular ones.<br /><br />Actually we probably are looking at higher eccentricity ones as being easier to get to, but I want to look at these first to get a handle on just how low the dV can be and just how long you have to wait.<br /><br />The horseshow orbit is confusing. IIRC the trick is to remember that the frame of reference in which the horseshoe is traced is rotating. <br /><br />edit: Dang it! Those orbit diagrams aren't working for me for some reason. I really really need to get a new PC <div class="Discussion_UserSignature"> </div>

 

[imadd]

anybody interested in a space ship larger than a battleship that will not need super accelleration to reach space ?

 

[craig42]

Build the station in orbit of the Asteroid, can easily get resources, and have 1g as well as 0g. We can always ship any surplus water to Luna colony.

 

[chriscdc]

Well yes, but huh!<br />If you mean Orion, then sorry it won't happen unless there was a really pressing need to get lots of people off the planet within the next decade.<br />You could use the asteroids as space ships but it would be easier to build space ships on the asteroid. You could use one as a generation starship but by then you might as well build such a large ship. <br /><br />Now to everyone else. What sort of machinery do you need to build a manned space module? No frills like computers or life support, just to hold the air in.<br />I was wondering if you could use organic material to make the pressure bubble eg a transhab. If you can use something like rubber then manufacture could be rather easy. Just GM some microbe to excrete rubber. The advantage is that just outside you have the perfect test environment.<br /><br />One device to build would be a industrial mass spectrometer. What I mean is a cross between a MS and ion deposit machine. Use sunlight to heat up the material in question. The UV should ionise the surface nicely. Use magnetic and electric fields to sort out the ions. You can grow diamonds or silicon wafers to act as substrates for low grade microelectronics eg solar voltaic cells. It will be slow and use alot of power. It may not be the easiest way to do it but advanced chemistry will take alot of research to be able to do in 0g and you are unlikelly to run out of raw materials. Does anyone have any links to any research the ISS might have done on this?

 

[chriscdc]

The problem is that you lose the advantage of the protection the asteroid provides. To get 1 g you will need to spin the station, which gives you another set of problems. Your in orbit so you can't just drop a wire down to the asteroid, you might be able to for fun or an extreme sport but not for regular use. If the asteroid is large enough then the habitable area could be large enough to hold a spinning section.<br /><br />That got me wondering about the gyroscopic effect of the spinning section on the asteroids rotation. Would it be possible to put the spin under control if we manufactrured magnetic disks that could be spun up to try and take some of the angular momentum from the asteroid? Once the disk is spun up as far as it can go you strap a rocket to it and get rid of it. then load in the next one. Would this be easier than to just use a simple mass accelerator.

 

[j05h]

Chris, <br /><br />I didn't explain myself fully. The idea is that there is a tunnelling machine that plugs the top of the tunnel. Outgassing needs to be minimized, every kilo of water that escapes is money out the window. The mirrors are directly over the tunnel in a "flower" configuration, directed to a stack of Sterling engines (or solarpanels) and a mirror array that concentrates and directs the light down through the tunnelling machine. The goal is to create a 10-30 meter tunnel with a large chamber of liquid at the end. The tunneller has pumps and sucks up liquid and vapor, filters it and pumps water out to waiting tugs for transport. The configuration I've played with has the powerplant as part of each tug, so the equipment sees a limited period of use on the comet surface. This setup allows the water to be processed in place, rock/clay to be reused and provides a long-term use of large tunnels for human occupation.<br /><br />Cutting material is going to be complex in zero-g, I'm still working through the methods for attaching the miner for initial tunnelling. Unless you plan on using lasers, physical contact has all sorts of issues. My current favorites are an impact net, "Manta" earth-anchors and using several distant mirrors to vaporize the top layer of the target location. The last option allows the tunneller to (potentially) hit a slushy/liquid spot, then freeze in place. Spin-up and active drilling proceed after it is anchored. Hope this helps explain it. <br /><br />How do you propose cutting blocks out of the comet/asteroid?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[j05h]

for spin-G on NEOs, I recommend digging out a chamber for a simple centrifuge. The centrifuge is simple, an axis, an electric motor and spokes leading out to the platform. An alternative is a large-diameter Bigelow-type inflatable with centrifuge, tied into a crater and covered in regolith. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[chriscdc]

To cut the blocks I suggest drilling a number of holes. At an angle so they all meet. You then fill the holes with an explosive. Detonate and the a chunk should have been removed. Of course the drill bits would be worn down but they would last longer than another method that I can think of.<br />The problem with using lasers or light from the sun is that the vaporised material can only get out one way (unless you are cutting at a shallow angle near the surface). In order for the material to disintergrate you have to give it alot of energy. There is no gas so the particles do not slow down and so hit the glass and burrow into it. Therefore making it possible to clean it off the glass.<br /><br />Perhaps we have our wires crossed. The digging I describe will be to remove material to make space for a base, underneath the surface of the asteroid. I think you are talking about a solar furnace to remove water from the rocks. If so then the set up you describe will work.